1. Field of the Invention
The present invention relates to a cover used in a head-up display, and to a display unit for a vehicle using the cover.
2. Description of the Related Art
Recently, a head-up display has been used in a vehicle for displaying a virtual image of data, which is not allowed to be displayed on a meter unit due to its narrow space, on a windshield so that a driver can visually recognize the virtual image superimposed on a foreground image which is seen through the windshield. Japanese published patent application No. 2005-75230 discloses one of conventional head-up displays. This conventional head-up display (HUD) includes a dust cover (a shutter as a protecting member), and a cleaning member for removing foreign particles from a displaying member.
Conventionally, the HUD includes a dust cover for preventing dust from entering an inside of the HUD. If this cover is thin, a vehicle driver may unintentionally break the cover, or heat may deform the cover. Further, it is difficult to form such a thin cover. Therefore, there is a demand to use a thick cover.
However, if the cover is thick, displaying light is reflected on inner surfaces of the cover, and reaches an eye point of a vehicle so that a driver watches a doubled virtual image on the windshield. We found that as a thickness of the cover increases, intensity of the reflected light increases.
Accordingly, an object of the present invention is to provide a cover for a head-up display and a display unit for a vehicle to prevent foreign objects from entering an inside of the display and to prevent a ghost from occurring even with a thick cover.